The present invention relates to hole saw pilot or guide devices, and more particularly to pilot and guide devices for use of a hole saw on a work piece with an existing hole.
Hole saws are typically manufactured as a cylindrical cup with a front peripheral cutting edge and a rear centrally located hub and arbor for attachment to a drill chuck. Cutting a hole in a work piece using a hole saw without a guide usually risks the hole saw ‘walking’ and creating scratches on the exterior surface of the work piece or producing a hole that may unintentionally be slanted (ie., not perpendicular) relative the exterior surface of the work piece. To solve this problem, hole saws are fitted with pilot bits to increase the accuracy of the hole saw. However, pilot bits are not useful when a hole saw is needed to create a new larger hole in a work piece that has an existing hole.
Several functional guides for piloting a hole saw to create a new larger hole in a work piece with an existing hole have been disclosed, for example, in U.S. Pat. No. 5,743,682 (issued 28 Apr. 1998), U.S. Pat. No. 5,871,310 (issued 16 Feb. 1999), U.S. Pat. No. 6,305,885 (issued 23 Oct. 2001), U.S. Pat. No. 6,409,437 (issued 25 Jun. 2002) and US Patent Publication Nos. 2012/0237306 (published 20 Sep. 2012) and 2103/0209187 (published 15 Aug. 2013). However, each of these guides are deficient in either not providing a firm seating of the guide within the existing hole or lacking clearance space between the guide and the rear of the cylindrical cup of the hole saw.
From the above, it is therefore seen that there exists a need in the art to overcome the deficiencies and limitations described herein and above.